com.rotty3000.websocket.demo.WebsocketEndpoint.java Source code

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Here is the source code for com.rotty3000.websocket.demo.WebsocketEndpoint.java

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/**
 * Copyright 2016 Raymond Aug
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.rotty3000.websocket.demo;

import java.io.File;
import java.io.FileInputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.LinkedList;

import javax.websocket.CloseReason;
import javax.websocket.Endpoint;
import javax.websocket.EndpointConfig;
import javax.websocket.MessageHandler;
import javax.websocket.RemoteEndpoint.Async;
import javax.websocket.Session;

import org.json.JSONObject;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.ServiceScope;

@Component(property = {
        "org.osgi.http.websocket.endpoint.path=/logger" }, scope = ServiceScope.PROTOTYPE, service = Endpoint.class)
public class WebsocketEndpoint extends Endpoint {

    @Override
    public void onOpen(Session session, EndpointConfig config) {
        Async remote = session.getAsyncRemote();

        session.addMessageHandler(new MessageHandler.Whole<String>() {

            public void onMessage(String text) {
                try {
                    JSONObject jsonObject = new JSONObject(text);

                    if (!jsonObject.has("file")) {
                        remote.sendText("[ERROR] No log file specified!");

                        return;
                    }

                    String fileName = jsonObject.getString("file");

                    Path filePath = Paths.get(fileName);
                    File file = filePath.toFile();

                    if (!file.exists() || !file.canRead()) {
                        remote.sendText("[ERROR] The file [" + fileName + "] cannot be found!");

                        return;
                    }

                    int lines = 0;
                    if (jsonObject.has("lines")) {
                        lines = jsonObject.getInt("lines");
                    }

                    remote.sendText(
                            "[CON] Here come the logs for [" + fileName + "] with [" + lines + "] of history.");

                    logReader = new LogReader(remote, file, lines);

                    logReader.start();
                } catch (Exception e) {
                    remote.sendText("[ERROR] " + e.getMessage());
                }
            }

        });
    }

    @Override
    public void onClose(Session session, CloseReason closeReason) {
        if (logReader != null) {
            logReader.stop();

            logReader = null;
        }
    }

    private LogReader logReader;

    class LogReader {

        LogReader(Async remote, File file, int lines) {
            this.remote = remote;
            this.file = file;
            this.lines = lines;
            this.string = String.format("%s#%s[%s]", name, this.hashCode(), file);
        }

        void start() throws Exception {
            Runnable task = () -> {
                try (FileInputStream in = new FileInputStream(file)) {
                    FileChannel fc = in.getChannel();
                    ByteBuffer bb = ByteBuffer.allocate(1024);
                    StringBuilder lineCurrent = new StringBuilder();
                    LinkedList<String> fifo = new LinkedList<String>();
                    int result;
                    boolean reachedFirstEOF = false;

                    while (!stop) {
                        result = fc.read(bb);
                        if (result == -1) {
                            if (!reachedFirstEOF && (lines > 0)) {
                                for (String line : fifo) {
                                    remote.sendText(line);
                                }
                                fifo.clear();
                            }
                            reachedFirstEOF = true;
                            Thread.sleep(400);
                            continue;
                        }
                        bb.flip();
                        while (bb.hasRemaining()) {
                            char c = (char) bb.get();
                            if ((c != '\n') && (c != '\r')) {
                                lineCurrent.append(c);
                            } else {
                                if (!reachedFirstEOF && (lines > 0)) {
                                    fifo.add(lineCurrent.toString());
                                    if (fifo.size() > lines) {
                                        fifo.removeFirst();
                                    }
                                } else if (lineCurrent.length() != 0) {
                                    remote.sendText(lineCurrent.toString());
                                }
                                lineCurrent = new StringBuilder();
                            }
                        }
                        bb.clear();
                    }
                } catch (Exception e) {
                    remote.sendText("[ERROR] " + e.getMessage());
                }
            };

            thread = new Thread(task);

            thread.setName(this.toString());

            System.out.println(this.toString() + " starting.");

            thread.start();
        }

        void stop() {
            System.out.println(this.toString() + " stoping.");

            stop = true;
        }

        @Override
        public String toString() {
            return string;
        }

        private final File file;
        private final int lines;
        private final Async remote;
        private volatile boolean stop = false;
        private final String string;
        private Thread thread;

    }

    private static final String name = LogReader.class.getSimpleName();

}